Reactor liquid cooldown apparatus

ABSTRACT

A reactor liquid cool down apparatus includes; a compressor comprising an inlet and an outlet, a first conduit connecting a reactor outlet to the compressor inlet, a mixing zone, comprising an inlet, an outlet, and a liquid cryogen inlet, a first control valve, a second conduit connecting the compressor outlet and the first control valve, a third conduit connecting the first control valve to the mixing zone inlet, a temperature control valve, a fourth conduit connecting the temperature control valve with the liquid cryogen inlet, a means for monitoring a mean fluid temperature within the second conduit, a second control valve, wherein the first control valve and the second control valve are configured to isolate the mixing zone, a fifth conduit connecting the second control valve with the mixing zone outlet, a sixth conduit connecting the second control valve to a reactor inlet, a bypass control valve.

RELATED APPLICATION

This patent application claims priority to U.S. Provisional PatentApplication Ser. No. 61/755,117 filed on Jan. 22, 2013, which is herebyincorporated by reference in its entirety.

BACKGROUND

In order to shorten downtime for turnarounds, refineries use coldnitrogen injected into reactor recycle loops to cool down reactorsquicker than with simply using the hydrocarbons in the system. Thissystem will reduce the amount of nitrogen required for most cooldowncycles by almost ⅔-increasing the value to the customer drastically.

Systems outfitted with piping of incompatible metallurgy are not able touse liquid nitrogen and the nitrogen must be vaporized and brought to aacceptable temperature before injecting into the customer's system(using mobile nitrogen vaporization units). Systems outfitted withstainless steel piping are able to inject liquid nitrogen directly,which requires far less nitrogen—usually around ⅓, but the majority ofcool downs are with cold gas. Both technologies are mature, althoughdirect injection generally requires a higher level of safetyconsciousness. Some customers with stainless piping are furtherreluctant to pursue liquid cooldowns because of the risk of recyclecompressor failure, or other failures that could result in liquidnitrogen reaching the reactor itself. The major drawback of cold gassystems is that the time it takes to perform the cool down to thecustomer's satisfaction, and the nitrogen usage—both of which offer anopportunity to create value for the customer through novel solutions.

SUMMARY

A reactor liquid cool down apparatus includes; a compressor comprisingan inlet and an outlet, a first conduit connecting a reactor outlet tothe compressor inlet, a mixing zone, comprising an inlet, an outlet, anda liquid cryogen inlet, a first control valve, a second conduitconnecting the compressor outlet and the first control valve, a thirdconduit connecting the first control valve to the mixing zone inlet, atemperature control valve, a fourth conduit connecting the temperaturecontrol valve with the liquid cryogen inlet, a means for monitoring amean fluid temperature within the second conduit, a second controlvalve, wherein the first control valve and the second control valve areconfigured to isolate the mixing zone, a fifth conduit connecting thesecond control valve with the mixing zone outlet, a sixth conduitconnecting the second control valve to a reactor inlet, a bypass controlvalve.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of one embodiment of the presentinvention.

Description of Preferred Embodiments

Illustrative embodiments of the invention are described below. While theinvention is susceptible to various modifications and alternative forms,specific embodiments thereof have been shown by way of example in thedrawings and are herein described in detail. It should be understood,however, that the description herein of specific embodiments is notintended to limit the invention to the particular forms disclosed, buton the contrary, the intention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

It will of course be appreciated that in the development of any suchactual embodiment, numerous implementation-specific decisions must bemade to achieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

The proposed solution may include a stainless piping skid that may bemounted on a non-DOT trailer (capable of being pulled by non-DOT pickuptrucks). The customer's entire recycle stream is redirected throughtemporary piping into the skid, where liquid nitrogen could be injectedwithout risk to the customer's piping.

The skid would include automatic bypass and isolation valves as well asa temperature control valve and multiple thermocouples (for votingpurposes). The customer's stream would enter the skid through the firstisolation valve. After a sufficient length of pipe to ensure adequatemixing, the combined stream would pass over three thermocouples beforeexiting the skid through the second isolation valve back Into thecustomer's piping.

The thermocouples would be used to isolate and bypass the skid in theevent a predetermined low temperature limit was reached (to be agreedupon with the customer—2 out of 3 voting). The liquid nitrogen wouldenter the piping via a temperature control valve—the thermocouples wouldalso be used as the control point (also to be agreed upon with thecustomer). Liquid nitrogen pressure would be provided by a small mobilenitrogen pumping and vaporization unit or simply the centrifugal pump onthe liquid nitrogen transport. The skid would be controlled by a simplePLC. Power and air would be provided by the transport or pumper. In thismanner, customers with incompatible piping in their existing systemwould be able to enjoy the benefits of liquid cool down.

Turning to FIG. 1, reactor 101 is to be cooled down. In one embodimentof the present invention, the outlet 103 of reactor 101 is attached tothe inlet 105 of compressor 104, by means of first conduit 107. In oneembodiment of the present invention, means 116A for monitoring a meanfluid temperature (such as a temperature sensor, thermocouple,thermistor, etc) senses the mean fluid temperature within conduit 112,and transfers this temperature information to temperature control valves114, and control valves 111, 117, and by-pass control valve 119 asneeded. In another embodiment of the present invention, means 116B formonitoring a mean fluid temperature (such as a temperature sensor,thermocouple, thermistor, etc) senses the mean fluid temperature withinmixing zone 107, and transfers this temperature information totemperature control valves 114, and control valves 111, 117, and by-passcontrol valve 119 as needed.

Compressor outlet 106 is connected to second conduit 112, which is thenconnected to first control valve 111. First control valve 111 isconnected to third conduit 113 which is connected to the inlet 108 tomixing zone 107. Mixing zone 107 may be made of stainless steel.

Temperature control valve 115 is connected to fourth conduit 115, whichis then connected to the cryogenic inlet line 110 of mixing zone 107.The outlet 109 of mixing zone 107 is connected to conduit 118, which isthen connected to second control valve 117. Second control valve 117 isthen connected to fifth conduit 118, which is then connected to inlet102 of reactor 101.

Temperature control valve 114 is connected to fourth conduit 115 whichis then connected to liquid cryogen inlet 110. The liquid cryogen may beliquid nitrogen.

If the mixing zone 107 must be bypassed, first control valve 111,temperature control valve 114 and second control valve 117 may beclosed, and bypass valve 119 may be opened.

A reactor liquid cool down apparatus, comprising;

-   -   a compressor (104), wherein said compressor comprises an inlet        (105) and an outlet (106),    -   a first conduit (107) connecting a reactor outlet (103) to the        compressor inlet (105),    -   a mixing zone (107), wherein the mixing zone (107) has an inlet        (108), an outlet (109), and a liquid cryogen inlet (110),    -   a first control valve (111),    -   a second conduit (112) connecting the compressor outlet (106)        and the first control valve (111),    -   a third conduit (113) connecting the first control valve (111)        to the mixing zone inlet (108),    -   a temperature control valve (114),    -   a fourth conduit (115) connecting the temperature control valve        (114) with the liquid cryogen inlet (110),    -   a means (116) for monitoring a mean fluid temperature within the        second conduit (112) or mixing zone (107)    -   a second control valve (117), wherein the first control valve        (111) and the second control valve (117) are configured to        isolate the mixing zone (107),    -   a fifth conduit (118) connecting the second control valve (117)        with the mixing zone outlet (109),    -   a sixth conduit (118) connecting the second control valve (117)        to a reactor inlet (102),    -   a bypass control valve (119), wherein the bypass valve (119) is        configured to bypass the mixing zone (107).

The reactor liquid cool down apparatus, wherein the mixing zone (107) isstainless steel.

What is claimed is:
 1. A reactor liquid cool down apparatus, comprising;a compressor, wherein said compressor comprises an inlet and an outlet,a first conduit connecting a reactor outlet to the compressor inlet, amixing zone, wherein the mixing zone comprises an inlet, an outlet, anda liquid cryogen inlet, a first control valve, a second conduitconnecting the compressor outlet and the first control valve, a thirdconduit connecting the first control valve to the mixing zone inlet, atemperature control valve, a fourth conduit connecting the temperaturecontrol valve with the liquid cryogen inlet, a means for monitoring amean fluid temperature within the second conduit, a second controlvalve, wherein the first control valve and the second control valve areconfigured to isolate the mixing zone, a fifth conduit connecting thesecond control valve with the mixing zone outlet, a sixth conduitconnecting the second control valve to a reactor inlet, a bypass controlvalve, wherein the bypass valve is configured to bypass the mixing zone.2. The reactor liquid cool down apparatus of claim 1, wherein the mixingzone is stainless steel.
 3. A reactor liquid cool down apparatus,comprising; a compressor, wherein said compressor comprises an inlet andan outlet, a first conduit connecting a reactor outlet to the compressorinlet, a mixing zone, wherein the mixing zone comprises an inlet, anoutlet, and a liquid cryogen inlet, a first control valve, a secondconduit connecting the compressor outlet and the first control valve, athird conduit connecting the first control valve to the mixing zoneinlet, a temperature control valve, a fourth conduit connecting thetemperature control valve with the liquid cryogen inlet, a means formonitoring a mean fluid temperature within the mixing zone, a secondcontrol valve, wherein the first control valve and the second controlvalve are configured to isolate the mixing zone, a fifth conduitconnecting the second control valve with the mixing zone outlet, a sixthconduit connecting the second control valve to a reactor inlet, a bypasscontrol valve, wherein the bypass valve is configured to bypass themixing zone.
 4. The reactor liquid cool down apparatus of claim 3,wherein the mixing zone is stainless steel.